ASA AnyConnect Double Authentication with Certificate Validation, Mapping, and Pre Fill Configuration Guide

Transcription

1 ASA AnyConnect Double Authentication with Certificate Validation, Mapping, and Pre Fill Configuration Guide Document ID: Contributed by Michal Garcarz, Cisco TAC Engineer. Jun 13, 2013 Contents Introduction Prerequisites Requirements Components Used Configure Certificate for AnyConnect Certificate Installation on ASA ASA Configuration for Single Authentication and Certificate Validation Test ASA Configuration for Double Authentication and Certificate Validation Test ASA Configuration for Double Authentication and Pre Fill Test ASA Configuration for Double Authentication and Certificate Mapping Test Troubleshoot Valid Certificate Not Present Related Information Introduction This document describes a configuration example for Adaptive Security Appliance (ASA) Cisco AnyConnect Secure Mobility Client access that uses double authentication with certificate validation. As an AnyConnect user, you must provide the correct certificate and credentials for the primary and secondary authentication in order to get VPN access. This document also provides an example of certificate mapping with the pre fill feature. Prerequisites Requirements Cisco recommends that you have knowledge of these topics: Basic knowledge of ASA command line interface (CLI) configuration and Secure Socket Layer (SSL) VPN configuration

2 Basic knowledge of X509 certificates Components Used The information in this document is based on these software versions: Cisco Adaptive Security Appliance (ASA) software, version 8.4 and later Windows 7 with Cisco AnyConnect Secure Mobility Client 3.1 It is assumed that you used an external Certificate Authority (CA) in order to generate: A public key cryptography standard #12 (PKCS #12) base64 encoded certificate for ASA (anyconnect.pfx) A PKCS #12 certificate for AnyConnect Configure Note: Use the Command Lookup Tool (registered customers only) in order to obtain more information on the commands used in this section. Certificate for AnyConnect In order to install an example certificate, double click the anyconnect.pfx file, and install that certificate as a personal certificate. Use the Certificate Manager (certmgr.msc) in order to verify the installation: By default, AnyConnect tries to find a certificate in the Microsoft user store; there is no need to make any changes in the AnyConnect profile. Certificate Installation on ASA This example shows how ASA can import a base64 PKCS #12 certificate: BSNS ASA (config)# crypto ca import CA pkcs

3 Enter the base 64 encoded pkcs12. End with the word "quit" on a line by itself: MIIJAQIBAzCCCMcGCSqGSIb3DQEHAaCCCLgEggi0MIIIsDCCBa8GCSqGSIb3DQEH... <output ommitted>... 83EwMTAhMAkGBSsOAwIaBQAEFCS/WBSkrOIeT1HARHbLF1FFQvSvBAhu0j9bTtZo 3AICCAA= quit INFO: Import PKCS12 operation completed successfully Use the show crypto ca certificates command in order to verify the import: BSNS ASA (config)# show crypto ca certificates CA Certificate Status: Available Certificate Serial Number: 00cf946de20d0ce6d9 Certificate Usage: General Purpose Public Key Type: RSA (1024 bits) Signature Algorithm: SHA1 with RSA Encryption Issuer Name: cn=tac ou=rac o=tac l=warsaw st=maz c=pl Subject Name: cn=tac ou=rac o=tac l=warsaw st=maz c=pl Validity Date: start date: 08:11:26 UTC Nov end date: 08:11:26 UTC Nov Associated Trustpoints: CA Certificate Status: Available Certificate Serial Number: 00fe9c3d61e131cda9 Certificate Usage: General Purpose Public Key Type: RSA (1024 bits) Signature Algorithm: SHA1 with RSA Encryption Issuer Name: cn=tac ou=rac o=tac l=warsaw st=maz c=pl Subject Name: cn=ios ou=unit o=tac l=wa st=maz c=pl Validity Date: start date: 12:48:31 UTC Nov end date: 12:48:31 UTC Nov Associated Trustpoints: CA

4 Note: The Output Interpreter Tool (registered customers only) supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output. ASA Configuration for Single Authentication and Certificate Validation ASA uses both authentication, authorization, and accounting (AAA) authentication and certificate authentication. Certificate validation is mandatory. AAA authentication uses a local database. This example shows single authentication with certificate validation. ip local pool POOL username cisco password cisco webvpn enable outside anyconnect image disk0:/anyconnect win k9.pkg 1 anyconnect enable tunnel group list enable group policy Group1 internal group policy Group1 attributes vpn tunnel protocol ssl client ssl clientless address pools value POOL tunnel group RA type remote access tunnel group RA general attributes authentication server group LOCAL default group policy Group1 authorization required tunnel group RA webvpn attributes authentication aaa certificate group alias RA enable In addition to this configuration, it is possible to perform Lightweight Directory Access Protocol (LDAP) authorization with the username from a specific certificate field, such as the certificate name (CN). Additional attributes can then be retrieved and applied to the VPN session. For more information on authentication and certificate authorization, refer to "ASA Anyconnect VPN and OpenLDAP Authorization with Custom Schema and Certificates Configuration Example." Test Note: The Output Interpreter Tool (registered customers only) supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output. In order to test this configuration, provide the local credentials (username cisco with password cisco). The certificate must be present:

5 Enter the show vpn sessiondb detail anyconnect command on the ASA: BSNS ASA (config tunnel general)# show vpn sessiondb detail anyconnect Session Type: AnyConnect Detailed Username : cisco Index : 10 Assigned IP : Public IP : Protocol : AnyConnect Parent SSL Tunnel DTLS Tunnel License : AnyConnect Premium Encryption : RC4 AES128 Hashing : none SHA1 Bytes Tx : Bytes Rx : Pkts Tx : 16 Pkts Rx : 192 Pkts Tx Drop : 0 Pkts Rx Drop : 0 Group Policy : Group1 Tunnel Group : RA Login Time : 10:16:35 UTC Sat Apr Duration : 0h:01m:30s Inactivity : 0h:00m:00s NAC Result : Unknown VLAN Mapping : N/A VLAN : none AnyConnect Parent Tunnels: 1 SSL Tunnel Tunnels: 1 DTLS Tunnel Tunnels: 1 AnyConnect Parent: Tunnel ID : 10.1 Public IP : Encryption : none TCP Src Port : TCP Dst Port : 443 Auth Mode : Certificate and userpassword Idle Time Out: 30 Minutes Idle TO Left : 28 Minutes Client Type : AnyConnect Client Ver : Bytes Tx : Bytes Rx : 1696 Pkts Tx : 8 Pkts Rx : 4 Pkts Tx Drop : 0 Pkts Rx Drop : 0 SSL Tunnel:

6 Tunnel ID : 10.2 Assigned IP : Public IP : Encryption : RC4 Hashing : SHA1 Encapsulation: TLSv1.0 TCP Src Port : TCP Dst Port : 443 Auth Mode : Certificate and userpassword Idle Time Out: 30 Minutes Idle TO Left : 28 Minutes Client Type : SSL VPN Client Client Ver : Cisco AnyConnect VPN Agent for Windows Bytes Tx : 5037 Bytes Rx : 2235 Pkts Tx : 4 Pkts Rx : 11 Pkts Tx Drop : 0 Pkts Rx Drop : 0 DTLS Tunnel: Tunnel ID : 10.3 Assigned IP : Public IP : Encryption : AES128 Hashing : SHA1 Encapsulation: DTLSv1.0 UDP Src Port : UDP Dst Port : 443 Auth Mode : Certificate and userpassword Idle Time Out: 30 Minutes Idle TO Left : 29 Minutes Client Type : DTLS VPN Client Client Ver : Bytes Tx : 0 Bytes Rx : Pkts Tx : 0 Pkts Rx : 177 Pkts Tx Drop : 0 Pkts Rx Drop : 0 NAC: Reval Int (T): 0 Seconds Reval Left(T): 0 Seconds SQ Int (T) : 0 Seconds EoU Age(T) : 92 Seconds Hold Left (T): 0 Seconds Posture Token: Redirect URL : Note: Refer to Important Information on Commands before you use debug commands. In this example, the certificate was not cached in the database, a corresponding CA has been found, the correct Key usage was used (ClientAuthentication), and the certificate has been validated successfully: debug aaa authentication debug aaa authorization debug webvpn 255 debug webvpn anyconnect 255 debug crypto ca 255 Detailed debug commands, such as the debug webvpn 255 command, can generate many logs in a production environment and place a heavy load on an ASA. Some WebVPN debugs have been removed for clarity: CERT_API: Authenticate session 0x0934d687, non blocking cb=0x cfc50 CERT API thread wakes up! CERT_API: process msg cmd=0, session=0x0934d687 CERT_API: Async locked for session 0x0934d687 CRYPTO_PKI: Checking to see if an identical cert is already in the database... CRYPTO_PKI: looking for cert in handle=0x00007ffd8b80ee90, digest= ad 3d a2 da e0 ee d9 b5 2a 83 5c dd e0 70.=...*.\..p CRYPTO_PKI: Cert record not found, returning E_NOT_FOUND CRYPTO_PKI: Cert not found in database. CRYPTO_PKI: Looking for suitable trustpoints... CRYPTO_PKI: Storage context locked by thread CERT API CRYPTO_PKI: Found a suitable authenticated trustpoint CA. CRYPTO_PKI(make trustedcerts list)crypto_pki:check_key_usage: ExtendedKeyUsage OID =

7 CRYPTO_PKI:check_key_usage:Key Usage check OK CRYPTO_PKI: Certificate validation: Successful, status: 0. Attempting to retrieve revocation status if necessary CRYPTO_PKI:Certificate validated. serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,ou=security,o=cisco,l=krakow,st=pl,c=pl. CRYPTO_PKI: Storage context released by thread CERT API CRYPTO_PKI: Certificate validated without revocation check This is the attempt to find a matching tunnel group. There are no specific certificate mapping rules, and the tunnel group that you provide is used: CRYPTO_PKI: Attempting to find tunnel group for cert with serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,ou=security,o=cisco,l=krakow,st=pl, c=pl, issuer_name: cn=tac,ou=rac,o=tac,l=warsaw,st=maz,c=pl. CRYPTO_PKI: No Tunnel Group Match for peer certificate. CERT_API: Unable to find tunnel group for cert using rules (SSL) These are the SSL and general session debugs: %ASA : Device chooses cipher : RC4 SHA for the SSL session with client outside: /64435 %ASA : Validating certificate chain containing 1 certificate(s). %ASA : Identified client certificate within certificate chain. serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,ou=security,o=cisco,l=krakow, st=pl,c=pl. %ASA : Found a suitable trustpoint CA to validate certificate. %ASA : Certificate was successfully validated. serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,ou=security,o=cisco,l=krakow,st=pl, c=pl. %ASA : Certificate chain was successfully validated with warning, revocation status was not checked. %ASA : Device completed SSL handshake with client outside: /64435 %ASA : Looking for a tunnel group match based on certificate maps for peer certificate with serial number: 00FE9C3D61E131CDB1, subject name: cn=test1, ou=security,o=cisco,l=krakow,st=pl,c=pl, issuer_name: cn=tac,ou=rac,o=tac, l=warsaw,st=maz,c=pl. %ASA : Tunnel group search using certificate maps failed for peer certificate: serial number: 00FE9C3D61E131CDB1, subject name: cn=test1, ou=security,o=cisco,l=krakow,st=pl,c=pl, issuer_name: cn=tac,ou=rac,o=tac, l=warsaw,st=maz,c=pl. %ASA : AAA user authentication Successful : local database : user = cisco %ASA : AAA retrieved default group policy (Group1) for user = cisco %ASA : AAA transaction status ACCEPT : user = cisco %ASA : DAP: User cisco, Addr : Session Attribute aaa.cisco.grouppolicy = Group1 %ASA : DAP: User cisco, Addr : Session Attribute aaa.cisco.username = cisco %ASA : DAP: User cisco, Addr : Session Attribute aaa.cisco.username1 = cisco %ASA : DAP: User cisco, Addr : Session Attribute aaa.cisco.username2 = %ASA : DAP: User cisco, Addr : Session Attribute aaa.cisco.tunnelgroup = RA %ASA : DAP: User cisco, Addr , Connection AnyConnect: The following DAP records were selected for this connection: DfltAccessPolicy %ASA : Group <Group1> User <cisco> IP < > AnyConnect parent session started. ASA Configuration for Double Authentication and Certificate Validation This is an example of double authentication, where the primary authentication server is LOCAL, and the

8 secondary authentication server is LDAP. Certificate validation is still enabled. This example shows the LDAP configuration: aaa server LDAP protocol ldap aaa server LDAP (outside) host ldap base dn DC=test cisco,dc=com ldap scope subtree ldap naming attribute uid ldap login password ***** ldap login dn CN=Manager,DC=test cisco,dc=com server type openldap Here is the addition of a secondary authentication server: tunnel group RA general attributes authentication server group LOCAL secondary authentication server group LDAP default group policy Group1 authorization required tunnel group RA webvpn attributes authentication aaa certificate You do not see 'authentication server group LOCAL' in the configuration because it is a default setting. Any other AAA server can be used for 'authentication server group.' For 'secondary authentication server group,' it is possible to use all AAA servers except for a Security Dynamics International (SDI) server; in that case, the SDI could still be the primary authentication server. Test Note: The Output Interpreter Tool (registered customers only) supports certain show commands. Use the Output Interpreter Tool in order to view an analysis of show command output. In order to test this configuration, provide the local credentials (username cisco with password cisco) and LDAP credentials (username cisco with password from LDAP). The certificate must be present:

9 Enter the show vpn sessiondb detail anyconnect command on the ASA. Results are similar to those for single authentication. Refer to "ASA Configuration for Single Authentication and Certificate Validation, Test." s for WebVPN session and authentication are similar. Refer to "ASA Configuration for Single Authentication and Certificate Validation,." One additional authentication process appears: %ASA : AAA user authentication Successful : local database : user = cisco %ASA : Built outbound TCP connection 1936 for outside: /389 ( /389) to identity: /54437 ( /54437) %ASA : AAA user authentication Successful : server = : user = cisco %ASA : AAA retrieved default group policy (Group1) for user = cisco %ASA : AAA transaction status ACCEPT : user = cisco s for LDAP show details that might vary with the LDAP configuration: [34] Session Start [34] New request Session, context 0x00007ffd8d7dd828, reqtype = Authentication [34] Fiber started [34] Creating LDAP context with uri=ldap:// :389 [34] Connect to LDAP server: ldap:// :389, status = Successful [34] supportedldapversion: value = 3 [34] Binding as Manager [34] Performing Simple authentication for Manager to [34] LDAP Search: Base DN = [DC=test cisco,dc=com] Filter = [uid=cisco] Scope = [SUBTREE]

10 [34] User DN = [uid=cisco,ou=people,dc=test cisco,dc=com] [34] Server type for unknown no password policy [34] Binding as cisco [34] Performing Simple authentication for cisco to [34] Processing LDAP response for user cisco [34] Authentication successful for cisco to [34] Retrieved User Attributes: [34] cn: value = John Smith [34] givenname: value = John [34] sn: value = cisco [34] uid: value = cisco [34] uidnumber: value = [34] gidnumber: value = [34] homedirectory: value = /home/cisco [34] mail: value = jsmith@dev.local [34] objectclass: value = top [34] objectclass: value = posixaccount [34] objectclass: value = shadowaccount [34] objectclass: value = inetorgperson [34] objectclass: value = organizationalperson [34] objectclass: value = person [34] objectclass: value = CiscoPerson [34] loginshell: value = /bin/bash [34] userpassword: value = {SSHA}pndf5sfjscTPuyrhL+/QUqhK+i1UCUTy [34] Fiber exit Tx=315 bytes Rx=911 bytes, status=1 [34] Session End ASA Configuration for Double Authentication and Pre Fill It is possible to map certain certificate fields to the username that is used for primary and secondary authentication: username test1 password cisco tunnel group RA general attributes authentication server group LOCAL secondary authentication server group LDAP default group policy Group1 authorization required username from certificate CN secondary username from certificate OU tunnel group RA webvpn attributes authentication aaa certificate pre fill username ssl client secondary pre fill username ssl client group alias RA enable In this example, the client is using the certificate: cn=test1,ou=security,o=cisco,l=krakow,st=pl,c=pl. For primary authentication, the username is taken from the CN, which is why local user 'test1' was created. For secondary authentication, the username is taken from the organizational unit (OU, which is why user 'Security' was created on the LDAP server. It is also possible to force AnyConnect to use pre fill commands in order to pre fill the primary and secondary username. In a real world scenario, the primary authentication server is usually an AD or LDAP server, while the secondary authentication server is the Rivest, Shamir, and Adelman (RSA) server that uses token passwords. In this scenario, the user must provide AD/LDAP credentials (which the user knows), an RSA token password (which the user has) and a certificate (on the machine that is used).

11 Test Observe that you cannot change the primary or secondary username because it is pre filled from the certificate CN and OU fields: This example shows the pre fill request sent to AnyConnect: %ASA : Extraction of username from VPN client certificate has been requested. [Request 5] %ASA : Extraction of username from VPN client certificate has started. [Request 5] %ASA : Extraction of username from VPN client certificate has finished successfully. [Request 5] %ASA : Extraction of username from VPN client certificate has completed. [Request 5] %ASA : Extraction of username from VPN client certificate has been requested. [Request 6] %ASA : Extraction of username from VPN client certificate has started. [Request 6] %ASA : Extraction of username from VPN client certificate has finished successfully. [Request 6] %ASA : Extraction of username from VPN client certificate has completed. [Request 6] Here you see that authentication is using the correct usernames: %ASA : AAA user authentication Successful : local database : user = test1 %ASA : Built outbound TCP connection 2137 for outside: /389 ( /389) to identity: /46606 ( /46606) %ASA : AAA user authentication Successful : server = :

12 user = Security ASA Configuration for Double Authentication and Certificate Mapping It is also possible to map specific client certificates to specific tunnel groups, as shown in this example: crypto ca certificate map CERT MAP 10 issuer name co tac webvpn certificate group map CERT MAP 10 RA This way, all user certificates signed by the Cisco Technical Assistance Center (TAC) CA are mapped to a tunnel group named 'RA.' Note: Certificate mapping for SSL is configured differently than certificate mapping for IPsec. For IPsec, it is configured using 'tunnel group map' rules in global config mode. For SSL, it is configured using 'certificate group map' under webvpn config mode. Test Observe that, once certificate mapping is enabled, you do not need to choose tunnel group anymore: In this example, the certificate mapping rule allows the tunnel group to be found: %ASA : Looking for a tunnel group match based on certificate maps for peer certificate with serial number: 00FE9C3D61E131CDB1, subject name: cn=test1, ou=security,o=cisco,l=krakow,st=pl,c=pl, issuer_name: cn=tac,ou=rac,o=tac, l=warsaw,st=maz,c=pl. %ASA : Tunnel group match found. Tunnel Group: RA, Peer certificate:

13 serial number: 00FE9C3D61E131CDB1, subject name: cn=test1,ou=security,o=cisco, l=krakow,st=pl,c=pl, issuer_name: cn=tac,ou=rac,o=tac,l=warsaw,st=maz,c=pl. Troubleshoot This section provides information you can use in order to troubleshoot your configuration. Valid Certificate Not Present After you remove a valid certificate from Windows7, AnyConnect cannot find any valid certificates: On the ASA, it looks like the session is terminated by the client (Reset I): %ASA : Built inbound TCP connection 2489 for outside: /52838 ( /52838) to identity: /443 ( /443) %ASA : Starting SSL handshake with client outside: /52838 for TLSv1 session. %ASA : Device supports the following 4 cipher(s). %ASA : Cipher[1] : RC4 SHA %ASA : Cipher[2] : AES128 SHA %ASA : Cipher[3] : AES256 SHA %ASA : Cipher[4] : DES CBC3 SHA %ASA : SSL client outside: /52838 proposes the following 8 cipher(s). %ASA : Cipher[1] : AES128 SHA %ASA : Cipher[2] : AES256 SHA %ASA : Cipher[3] : RC4 SHA %ASA : Cipher[4] : DES CBC3 SHA %ASA : Cipher[5] : DHE DSS AES128 SHA %ASA : Cipher[6] : DHE DSS AES256 SHA %ASA : Cipher[7] : EDH DSS DES CBC3 SHA %ASA : Cipher[8] : RC4 MD5 %ASA : Device chooses cipher : RC4 SHA for the SSL session with client outside: /52838 %ASA : Teardown TCP connection 2489 for outside: /52838 to identity: /443 duration 0:00:00 bytes 1448 TCP Reset I

14 Related Information Configuring Tunnel Grouips, Group Policies, and Users: Configuring Double Authentication Configuring an External Server for Security Appliance User Authorization Technical Support & Documentation Cisco Systems Updated: Jun 13, 2013 Document ID: